Stranding apparatus



Oct. 24, 1967 H. BURR 3,348,369

STRANDING APPARATUS Filed April 26, 1965 HARVEY BURR f MM f/IS Mil/f I N VENTOR.

United States Patent 9 3,348,369 STRANDING APPARATUS Harvey Burr, De Kalb, Ill., assignor to Anaconda Wire and Cable Company, a corporation of Delaware Filed Apr. 26, 1965, Ser. No. 450,668 7 Claims. (Cl. 5758.7)

ABSTRACT OF THE DISCLOSURE A stranding means is equipped with a feed capstan and a take-up capstan and the feed capstan is operated at a speed greater than the take-up capstan.

Y My invention relates to stranding apparatus and particularly to such apparatus comprising novel strand advancing means.

In the cabling art it has long been known to twist a plurality of strands together by means of a fiyer that supports a loop of the stranded material and rotates it around a take-up reel. The lay of the strand twist depends upon the number of rotations made by the fiyer per unit advance of the stranded material onto the take-up reel, and, when it is important to have a uniform length of lay, the take-up reel is fed by a capstan of some type that meters the stranded material onto the reel at a preselected constant speed. The flyer usually takes the form of an arch or bow and the metering capstan has the effect of dragging the stranded material around this bow. This dragging effect stretches the conductors and increases their electrical resistance.

My apparatus has special advantage for the manufacture of telephone cable pairs where the telephone wires are insulated with paper applied in a tubular spiral. In this case the strandingoperation is continuous with the operation of applying the paper insulation and has particular economic advantage in that it eliminates the customary intermediate steps of reeling and unreeling, I have discovered that it is an advantage in this process of insulating telephone wires to apply the paper while the wires are under slight tension. When this tension is relaxed it has the effect of bunching up the paper somewhat and relieving the strain that the paper may undergo due to twisting. But this is only true if the relaxation of tension takes place before the strand has been twisted.

I have discovered that I can overcome the tendency to elongate the conductors and also relieve the strain in the wires prior to twisting by interposing a smooth surfaced capstan immediately upstream of the rotating elements of my strander, wrapping the insulated wires around the capstan and turning it at a speed that exceeds the speed of the metering capstan that pays the twisted wires onto the take-up reel.

My stranding apparatus thus comprises a cradle, storage means supported by the cradle, and metering means also supported by the cradle that meters twisted strand onto the storage means at a pre-selected rate of advance. The twisted strand comprises a plurality of individual wires such as insulated conductors. My apparatus also comprises a fiyer rotating around the cradle and supporting the strand, the strand being twisted by the rotation of the fiyer. Preferably the strand receives a double twist, being twisted upstream and again downstream of the fiyer. My apparatus also comprises a smooth-surfaced capstan upstream of the flyer having a surface speed greater than the rate of advance of the strand, the wires being wrapped around the capstan and advanced thereby but slipping on the capstan so as not to advance with it at speeds substantially exceeding the rate of advance imparted by the aforesaid metering means. Preferably the wires pay from the capstan so as to form a slack catenary loop under the capstan between the capstan and the fiyer. The angle of wrap of the wires decreases with increasing slackening of the catenary; the wires slip on the capstan when the catenary becomes sufiiciently slack, and advance with the capstan when the catenary has reduced slackness. By this means the catenary is automatically maintained slack paying into the fiyer. Preferably my capstan will have a surface speed from 1% to 6% in excess of the speed of advance of the strand of the metering means and the angle of wrap of the wires will be between 1000 and 1500 to provide the correct slippage.

A more thorough understanding of my invention may be gained from the appended drawing.

In the drawing:

FIGURE 1 is a side elevation of an apparatus of my invention.

FIGURE 2 is a plan view of the apparatus of FIGURE 1. My stranding apparatus comprises a strander, indicated generally by the numeral 10 of conventional construction wherein a ilyer 11 comprising a hollow shaft 12 upstream and a hollow shaft 13 downstream rotates in journals 16, 17, 18, 19, driven by a motor 21. The flyer 11 also comprises bows 22, 23 fastened to end plates 24, 26 that are rigidly fixed to the respective shafts 12, 13. To the inside of the how 22 there is aflixed a guide tube 27 and to inside of the how 23 there is affixed a second guide tube 28.

A cradle 29 is mounted on the shafts 12, 13 by means of bearings 31, 32 so that the cradle 29 can hold sub 'stantially level due to a low center of gravity, while the flyer-ll rotates around it. Within the cradle 29there is mounted a take-up reel 33 driven by a'motor 34 also mounted on the cradle 29 and electrically supplied by means of slip rings, not shown. The take-up reel 33 is driven at a relatively high speed through a slip clutch in a known manner so that it applies a selected tension to strand 36 being paid onto it, but the speed of the strand 36 which is maintained constant, is determined by a metering capstan 37 also mounted on the cradle 29. Traverse guide rolls 38 guide the strand evenly onto the reel 33. Although I have shown a reel take-up for my strander, it will be understood that other take-up means such a sa take-up into a drum package similar to that shown" in my Patent 3,079,747 can also be used. A line shaft 39 'is driven by means of chains and sprocket assemblies 41, 42 from the shafts 12, 13, and this in turn drives a capstan 43 through a gear-train 44 at a circumferential speed hetwen 1% and 6% greater than the circumferential speed of the capstan 37. The capstan 43 receives two insulated strands 46, 47 from guide sheaves 48, 49. The capstan 43 has a ground and polished cast iron surface of cylindrical shape and there are 8 coaxially mounted sheaves 51 guiding the conductors 46, 47 onto the surface of the capstan 43. As the two parallel conductors 46, 47, each of which is insulated with a spiral tube of paper, leave the sheaves 48, 49 they pass around the bottom of the capstan 43 for about and up onto the furthest left of the two sheaves, as seen facing downcapstan 43 in each case taking another turn of about 300, and then the two conductors pass to the last two sheaves from which they pass around the top of the capstan a final time and leave the bottom of the capstan in a catenary 52 leading into a forming die 53 of the strander where the strands are twisted together to form the twisted pair strand 36. In their last turn around the capstan 43 the conductors 46, 47 have an angle of contact with the capstan of about 180 if the catenary 52 takes the form of the solid line in FIGURE 1. Since, however, the surface of the capstan 43 is turning faster than the conductors are entering the forming die 53 slack is generated, in the catenary 52 which drops to the dashed line 52a. In this position the angle of contact of the last turn of the conductors around the capstan has been reduced toabout 90 and the conductors slip on the capst-an until the catenary is raised again by the action of the metering capstan 37 drawing the conductors into the strander. The capstan 43 is thus seen to be self-adjusting and to keep a slack feed into the strander at all times without special attention by an operator. The twisted strands pass over a sheave 54 and into the tube 28 which they leave to pass over another sheave 56. The sheaves 54, 56 are rotating with the fiyer 11 and as the strand 36 passes from the rotating sheave 56 to the stationary capstan 37 it receives a second twist having the same direction as the twist imparted in the die 53.

The insulated conductors paying onto the sheaves 48, 49 are under tension, being pulled by the capstan 43. But, since the capstan 43 turns faster than the strand is being taken up, the strand is slack as it enters the strander. This relaxation of tension reduces the length of the conductors relative to the surrounding insulation and permits the insulation to bunch up slightly. However, thestrand cannot become too slack or. the caten-ary 52 would drag on the ground. This is prevented by the slippage of the conductors on the surface of the capstan 43-when the caten-ary 52.becomes slack. I have found that the angle of contact of the conductors with the surface of the capstan 43 should beabout 1080 and in no case less than 1000 nor more'than 1500 to achieve the proper amount of slippage. This angle can be reduced,

by moving the rolls 51 mounted on a stand 57 more dis-- tant from the capstan 43, and increased by having the stand 57 closer to the capstan. It can be increased, of course, by taking another turn of the conductors 46, 47 around the capstan, and for this purpose, additional sheaves 51 can be added to the stand 57. Change gears of known type are provided in the gear train 44 to change the speed of the capstan 43 within the stated limits compared to the speed of the metering capstan 37.

I Although I have described my invention as applied to a horizontal double-twisted strander it will be understood that the strander 10 might have the reel 33 mounted lengthwise in the cradle 29 and thus impart only a single twist without departing from my invention and the strander might be mounted vertically instead of horizontally, also within the scope of my invention.

In the practical use of my invention the insulated conductors 46, 47 are threaded around the capstain 43 and the sheaves 51. It will be noted thatI have mounted the capstan and sheaves on cantilevered shafts to facilitate the stringing operation. When it is preferred, cords or lead wires may be substituted for the conductors 46, 47 during the preliminary stringing.

The conductors are strung through the forming die 53, over the sheave 54, through the tube 28 using a snake or stilt wire of known type, over the sheave 56, around the capstan 37, through the traverse guide rolls 38 and onto the take-up reel 33. When the motor 21 is then started the strand entering the tube 28 is found to be free from harmful tension and is automatically fed to the strander at the proper speed due to slippage on the capstan 43 without further attention from an operator.

The apparatus herein'above described is understood to be exemplary rather than definitive. Other embodiments and modifications coming within the full scope of my invention are defined in the following claims.

I claim:

1. Stranding apparatus comprising:

(A) a cradle,

(B) strorage means supported by said cradle,

(C) metering means supported by said cradle, metering twisted strand comprising a plurality of individual wires into said storage means at a preselected rate of advance,

(D) a flyer rotating around said cradle and supporting said strand,

(E) said strand being twisted by the rotation of said fiyer,

(F) a smooth-surfaced capstan upstream of said fiyer,

(a) said wires being wrapped around said capstan and advanced thereby,

(b) said wires being slippable on said captan so as not to advance therewith at speeds substantially exceeding said rate of advance, and

(G) means driving said capstan at a surface speed greater. than the speed of said metering means.

2. The apparatus of claim 1 wherein said capstan surface speed is 16% greater than said rateof advance.

3. The apparatus of claim 1 wherein said surface is polished and the angle of wrap of each of said Wires around said capstan is between 1000 and 1500.

4. Stranding apparatus comprising:

(A) a cradle,

(B) storage means supported by said cradle,

(C) metering means supported by said cradle, metering twisted strand comprising a. plurality of individual wires into said storage means at a preselected rate of advance,

(D) a fiyer rotating around said cradle and supporting said strand,

(E) said strand being twisted upstream and again downstream of said fiyer by the rotation thereof, I

(F) a smooth-surfaced capstan upstream of said fiyer,

(a) said wires being wrapped around said capstan and advanced thereby,

(b) said wires being slippable on said capstan so as not to advance therewith at speeds, substantially exceeding said rate of advance, and

(G) means driving said capstan at a surface speed greater than the speed of said metering means.

5. The apparatus of claim 4 wherein said capstan surface speed is 16% greater than said rate of advance.

6. The apparatus of claim 4 wherein said surface is polished and the angleof wrap of each ofsaid wires around said capstan is between 1000 and 15 00.

7. Stranding apparatus comprising: t (A) a cradle,

(B) storage means supportedby said cradle, (C) metering means supported by said cradle, metering twisted strand comprising a plurality of individual wires, into said storage means at-a preselected rate of advance, (D) a fiyer rotating around said cradle and supporting said strand, (E) said strand being twisted by the rotation of said fiyer, (F) a smooth-surfaced capstan upstream of said fiyer, (a) said wires being wrapped around said capstan and advanced thereby,

(b) said wires paying from said capstan so asto form a slack catenary loop under said capstan between said capstan and said fiyer,

(c) the angle of wrap of said wires around said capstan decreasing with increasing slackening of said catenary,

( d) said Wires slipping on said capstan upon said catenary becoming sulficiently slack and advancing with said capstan upon said catenary having reduced slackness, whereby said catenary is automatically maintained slack paying onto said flyer, and

(G) means driving said capstan at a surface speed greater than the speed of said metering means.

References Cited UNITED STATES PATENTS 2,862,351 12/1958 Riley 5790 Haugwitz 5758.7 X Haugwitz 5758.7 X Brutko 5790 Boussu et a1 57-58.7 X Demmel 5758.7 X L'aureti 5758.7 Blaisdell 5758.7 Blaisdell 5758.7

FOREIGN PATENTS Great Britain.

FRANK I. COHEN, Primary Examiner.

D. WATKINS, Assistant Examiner. 

1. STRANDING APPARATUS COMPRISING: (A) A CRADLE, (B) STORAGE MEANS SUPPORTED BY SAID CRADLE, (C) METERING MEANS SUPPORTED BY SAID CRADLE, METERING TWISTED STRAND COMPRISING A PLURALITY OF INDIVIDUAL WIRES INTO SAID STORAGE MEANS AT A PRESELECTED RATE OF ADVANCE, (D) A FLYER ROTATING AROUND SAID CRADLE AND SUPPORTING SAID STRAND, (E) SAID STRAND BEING TWISTED BY THE ROTATION OF SAID FLYER, (F) A SMOOTH-SURFACED CAPSTAN UPSTREAM OF SAID FLYER (A) SAID WIRES BEING WRAPPED AROUND SAID CAPSTAN AND ADVANCED THEREBY, (B) SAID WIRES BEING SLIPPABLE ON SAID CAPSTAN SO AS NOT TO ADVANCE THEREWITH AT SPEEDS SUBSTANTIALLY EXCEEDING SAID RATE OF ADVANCE, AND (G) MEANS DRIVING SAID CAPSTAN AT A SURFACE SPEED GREATER THAN THE SPEED OF SAID METERING MEANS. 